Hull fitting



HULL FITTING Filed Ma rch 4, 1945 A. T. NEWELL INVENTOR Aer/w Z 445714641.

BY I

.water under pressure which varies'w Patented Nov. 7, 1944 Keny'dn Instrument G0,; In c,-; Huntington Sta .tion; N Y.; a. corporation of New York 1 Claim; (01. ii -1&2?

cient hull fitting for a "ifi'r'ih speedometer; in

eluding a Pitot tube strut adapted to project beheath the hull of 5 wait; whfhis equipped with novetmeans for retrieving the tube through-the housing tube I, and to project beneath the bottom of hull 2, is shown in Fig. 3. This strut-com;

prises an elongated tube l2 having its lower end l3 closed and its upper end -fittedwith a gasket or stopper l4. Strut [2 may be of circular cross also be located at a point between the bow and the maximum beam of the boat or approximately forty feet aft of the bow if the boat has an overall length in excess of eighty feet. The assembly should furthermore be in a location where the gate valve 8 will be accessible from within the boat. There should also be sufiicient vertical height in the'boat to permit retrieving or withdrawing the strut as previously described.

The arrangement of the Pitot opening l6 and the Static openings I1 and i8, as described above,

is likewise important. In accordance with Bournellis Theorem, the pressure created on either side of the Static openings is equal and opposite duced in the Static side due only to a change section, or, if desired, it may have a stream lined cross section, as illustrated in, 4, to

reduce the drag of the strut in the water and indirection.- Thus, changes in pressure are pro- 3 of Static head on these openings. It is not af-. fected by water velocity around the strut, If

to cause a nonturbulent flow over the'Static openingsto be described. The strut 12 may be disposed vertically, or it may be inclined rearwardly at an angle of approximately 45? to prevent same from being fouled by seaweed or'oth'er debris. Preferably, the strut I2 is made of molded Bakelite or other .frangiblematerial which will break uppn grounding oi the vessel or hitting a solid obstacle, thus removing the danger of, hull damagevby tearingout the strut assembly. -As shown in Figs. 1,3 and .4 the lower end of strut I2 is provided with a Pitot opening 16 which is fairly large in diameter to prevent fouling by marine growth. This opening is fixed parallel tothe. fore ,andaft axis of the boat and is 10- catedso asto point directlylforward. The two Static openings I! and 18 are formed by a transverse hole which extends throughthe bottom of thestrut at its maximum width at right angles to the PitotEopenipg. ;-This Static opening is preferably located at the same distance below the waterline as thePitot opening, and a perpendicular hole within the strut intersects in a T with the Static openings as, shown in Fig.4.

A pair-of tubes or passages l9 and 20 extend through the strut [2, the former having its lower end connected-to the Pitot opening [6 and the latter having its ;1ower-j end connected to the Static openings, and i8, as shown in Figs. 1 and 4., The tubes 19 and 20 extend upwardly through-gasket atthe topof strut l2 and 5 v through a ferruleq2l andhave their upper ends secured to a valve block 25 by means of which said tubes are connected to the standpipe assembly of the system as hereinafter described.

The valve block 2,5 is spaced above the gasket M .to permit the strut l2 to be extended through the hullof theboat or to be retracted to a point above gate valve 8 in the housing tube I, gate valve 8 being closed after the strut has been retracted. -The strut I2 is then withdrawn by removing cap; ill from the top of, the strut housing tube I. Fig. 2 showsthe housing tube I with the strut removed therefrom and with gate valve 8 closed. Now, in: order toreinsert the strut I2 into housing tube l, ..the strut is lowered into tube], untilit rests upon gate valve 8 which is closed at. such time. Cap I0 and ferrule 2| are next drawndown to the top of tube 1 and the cap 10 is screwed in place, after which the gate valve 8 is opened and the strut is lowered in the strut must be in such aposition as .to insure its continual operation in solid water. It should 4 the strut has a stream-lined cross section, as

illustrated in Fig. 1, the Static openings should be located at the point of maximum ,width. 3

These holes should be of the same size as the Pitot opening, but this is not necessary if a smaller metering orifice is installed identical in size in each side of the system. I

Staadpipecssembly The respective Pitot'and Static tubes l9 and 20 of strut l2 are connected through valve block 25 to the Pitot line 26 and Static line 21-,-respectively, as shown in Fig. l. The Pitot line 26 contains an upright standpipe 28, and the Static line 21 contains a similar standpipe 28". The Pitot and Static lines also contain various valves as hereinafter described, and, since the various elements in these twolines are alike in all-respects, they will be given corresponding reference numerals except that the numerals identifying the elements in Static line 21 will have primes affixed thereto. v

The respective Pitot and Static lines 26 and 21 include shut-off cocks "30, 30 associated with valve block 25, shut-off cocks 3|, 3| at the'lowe'r ends of standpipes28, 28', blow-out valves 32, 32'. connected to the upper ends of the s'tandpipes, and shut-01f valves 33, 33' which connect the respective pneumatic" lines to the indicator 35. Standpipes 28,28 are placed wherever convenient in the boat, but they must be arranged at such a height in thejvessel that they will span or contain the normal waterline of the boat. They must also be located verticall'y with the shut-01f cocks 31, 3| at their lower ends, and for convenience they should 'be located, adjacent each other, in the sameplane and at the same height. The blowout valves 32, '32 and the shut-ofi valves 33, 33 should be located wherever conveniently accessihle, and still be close to the indicator as shown inFig. 1. The indicator 35 may be placed in any position and wherever desired in the boat. The above-enumerated elements of the Pitot v and Static lines are connected by suitable piping or tubing, for example one-quarter inch soft-rolled copper tubing such as iscommonly used for auto- .mobile gasoline lines,.oil lines, etc. Compression said shut-off cocks. 'within its housing tube I by lifting valve block swig-29s appropriately marked as with the' letters 'spectively, which permit a blow-outline to be connected to the system for blowing mud and other foreign accumulations from both-thePitot and Static lines as hereinafter described. Durin such. blow-out operation, the shut-o'fiw'alves 33, 33' must be closed to isolate theindicator'35 in order to prevent damage to the indicator. A cable 94 leads to a suitable light in the indicator 35.

Operation If the installation of the marine speedometer is made with the boat out of water, the strut I2 should be drawn within the strut housing tube I before launching, to prevent damage to this part.

To accomplish this, the shut-off cocks 30, 30' on valve block 25 should be closed, and the tubing of the Pitot and Static lines 26 and 21 below standpipes 28, 28 shouldbe disconnected from Strut I2 may now be raised 25, the tubes I9 and 20 sliding through the ferrule 2|. When launching has been completed, strut I2 should be forced out again to its normal operating position, and the tubing of the Pitot and Static lines should be reconnected to the shut-01f cocks 30, 30' as shown in Fig. 2. Ferrule 2 I may contain suitable packing to prevent leakage around tubes I9 and 20.

With the boat at rest in still water, all of the valves should be opened, and the drain cocks 31, 31' of blow-out valves 32, 32' should likewise be opened. Opening of drain cocks 31, 31' permits water to rise in the system to such a level as to be equal to the height of the waterline of the boat.

Therefore, the height of the water in the system should terminate in standpipes 28, 28 since these standpipes contain the normal waterline of the boat. After a few seconds with all valves open, drain cocks 31, 31' should be closed tightly. The speedometer system is now ready for operation.

It may be desired from time to time to clear the system of an impediment. This may be accomplished by connecting blow-out lines to the orifices 38, 38 of drain cocks 31, 31'. The procedure for this operation is as follows: Close the shutofi valves 33, 33' between the indicator and the drain cocks, and open the drain cocks 31, 31'. Apply air pressure to the orifices 38, 38 of the drain cocks, which will blow the water from the lower half of standpipes 28, 28, as well as from the tubing which leads to strut I2, and from the strut itself. During this blowing-out operation the shut-off cocks 3|, 3| at the lower ends of the standpipes, and the shut-off cocks 30, 30' at the upper end of the strut assembly must be in open position. Upon completion of this operation, the air lines should be disconnected from drain cocks 31, 31', and these drain cocks should be left open for a few seconds to permit the water to rise again in the system to the waterline in standpipes 28, 28', after which drain cocks 31, 31 should be closed tightly while leaving all of the various valves in open position.

The strut I2 may be removed while the boat is in operation by first closing the shut-01f cocks 38, 30', and then disconnecting the tubing'of the Pitot and Static lines from said shut-oif cocks as previously described. The strut I2 is then raised its" housing tub'e -I to a-h'eight which willi permit closing' of gate val-veil; With the gate valve:closed, no water can enter the hull. Using a pipe wrench, cap I is detached from strut housing tube I,'after-which*strut I2with the ferrule 2l and cap 'I limaylbe lifted out of said'housing tube. The strut may now 'be cleaned of zany-foul growth or corrosion and its tubes "I 9 and 2!! blown out.

To replace the" strut I2; simply reverse the =8 and push strut I2 downwardly "in tube:- =I -'until valve block is in the proper position. Next, attach the tubing of the Pitot and Static lines 26 and 21 to the respective shut-01f cocks 30, and then open both of said shut-off cocks. This'final operation of securing the tubes should be done with care so as not to confuse the Pitot and Static sides of the system, and to avoid possible confusion the respective sides of valve block 25 may be appropriately marked with suitable indicia. With all valves in open position, drain cocks 31, 31 should now be opened for a few seconds to permit water to rise again in both lines to its normal waterline in the standpipes 28, 28. Drain cocks 31, 31 may then be tightly closed, whereupon the system is again in condition for operation. As in all pneumatic and hydraulic systems, absolute tightness of the system must be achieved'if satisfactory operation is to be obtained. In normal operation, as previously described, drain cocks 31, 31' remain tightly closed,

' through the water inPitot tube I9 and the associated tubing of the Pitot line to standpipe 28 where a conversion from hydraulic to pneumatic pressure occurs, as previously described. The pressure is thence transferred by air pressure through the upper tubing of Pitot line 26 to the instrument 35 to indicate the speed of the boat in knots.

Compensation for changes in draft, pitching, rolling and temperature is accomplished by variations in pressure in the Static side of the system. The Static openings I1 and I8 of strut I2 are 10- cated-at the same level and at right angles to Pitot opening I6, hence the Static pressure side of the system produces a pressure equal and opposite to any positive pressures produced in the Pitot line which are not caused by a forward movement of the boat through the water. This correcting pressure compensates for the change of pressure resulting'from changes in draft, large waves, pitching, rolling and temperature. The Static system is in all respects the same as the Pitot system except that the former terminates in orifices at right angles to the direction of the motion of the boat.

Although a specific embodiment of the invention has been shown for purposes of illustration, it is to be understood that the invention is capable of various adaptations and that changes and modifications may be made therein as will be readily apparent to a person skilled in the art. Certain-specific terms are used for convenience only and not as alimitation of the scope of the invention. The invention is only to be limited in accordance with the scope of the appended claim. I

The invention claimed is: A hull fitting for a marine speedometer comprising an elongated strut having-at its lower end Pitot and Static openings, a pair of tubes extending upwardly from said strut-and communicating respectively with said openings, a strut housing tube to be attached to a hull and open to the outside water, a gate valve in said housing tube within said hull having an opening to pass said strut and spaced below the top of said housing tube to provide space for said strut to be ventirely retracted in said housing tube above said valve, a removable topelosure forsaid housing tube,.;said pair of tubesextending through said top closure for axial movement for retracting or extending said strut and maintaining a water tight seal to prevent leakage from said tube into said hull, and a valve block attached to the free ends of said p'air of tubes and having means to ARTHUR T. NEWELL. 

